Another potential difference - and one nobody has answered yet, is that the LP's in our trucks circulate diesel fuel thru the motor itself for lubrication and cooling - something possible with the low volatility of diesel fuels, with little danger of explosion due to brush arcing - but that ALSO means wear particles - brushes, shaft bushings, etc, - are ultimately circulated on towards the engine - hopefully to be caught and held by the fuel filter.
The QUESTION IS, do the Carter pumps as displayed above ALSO circulate fuel thru the motor, since THEY are presumably more often used to pump gasoline instead of diesel fuel, and gasoline is far more volatile and provides no lube?